Our study simulated 3 different tFUS scenarios: no correction for phases offset by the skull, corrections calculated from ray-tracing, and modeling of a virtual source followed by time-reversed phases to restore pressure at the target. TR corrected simulations had the smallest mean difference focal position and volume between rCT and sCT, but application of Kranion-calculated phases had the smallest peak pressure difference. Because the Kranion phases were dependent on the skull thicknesses from Kranion, which we found to be highly correlated between rCT and sCT, we expected the simulation results from applying the phases to be similar. The mean phase difference was smaller for phases calculated from Kranion than TR-corrected simulations, but the TR-corrected simulations more fully encapsulate the internal structure of the skull[1]}. Similar work has evaluated the skull correction performance capabilities of artificial skulls and applied the phases in an experimental context beyond modeling and simulations[2]}, [3]}, [4]}. One study reconstructed a virtual CT from a T1-weighted MR image and compared calculated phases from Insightec's ExAblate system, resulting in an average phase difference between the real and MR-generated CT of less than 1 radians and application of the phases was successfully demonstrated in thermal experiments using head phantoms[2]}. A study using the same transducer as Wintermark et al. compared UTE-derived MR images to real CT images of head phantoms and found no statistical difference between peak temperatures achieved for thermal experiments[3]}. Most recently, Leung et al. generated skulls from UTE images and calculated phases from the Insightec system but applied phases in a water bath setup, measuring the pressure field behind a skull using a hydrophone and reported comparable beam profile results when compared with real CTs[4]}.
